1. Field of the Invention
The present invention relates to a wireless radio communication system. In particular, the present invention relates to a data communication method between a base station and a wireless terminal in a radio communication system which can increase the transmission efficiency in case of bidirectionally transmitting data through a single channel between the base station and wireless terminal.
2. Description of the Related Art
Generally, the signal transmission system in a wireless radio communication system may be classified into a bidirectional transmission system and a unidirectional transmission system. The bidirectional transmission type communication system is applied to various type terminals such as wireless units for vehicles and cellular wireless units. The bidirectional transmission type wireless radio communication system is provided with a plurality of base stations serving as interfaces between the terminals in a predetermined number of cells. According to the bidirectional transmission system, a plurality of time slots each of which is composed of a predetermined number of bits (for example, 40 bits or symbols) are allocated to a transmission frame for transmitting data through a predetermined channel between the terminal and the base station, and the transmission of data, which is divided into slots, is bidirectionally performed at the same time. Here, the time slot means the time period during which a slot is transmitted. According to the present invention, the slot transmitted from the base station to the terminal is defined as a down-link slot, and the slot transmitted from the terminal to the base station is defined as an up-link slot.
According to the conventional system, in case that the information produced from a certain terminal or base station is transmitted bidirectionally, as shown in FIG. 1, the data frame tied in the unit of 40 bits is alternately and continuously transmitted in forward and backward directions during given slots D1, U1, D2, and U2. That is, the down-link slots and the up-link slots D1, U1, D2, and U2 are alternately and repeatedly transmitted at the same time.
The signal transmission system as described above is designed assuming that the amount of data, which is transmitted and received, between the originating side and the terminating side, is almost the same based on the wireless radio communication system for transmitting a voice signal, and nowadays, almost wireless radio communication systems use the transmission system as described above.
However, the radio information communication service merely providing a voice signal has been changed to the communication service for providing multimedia information such as a voice, video, and text information. Accordingly, the wireless radio communication system, which assumes that the ratio of the down-link slots to the up-link slots is almost xe2x80x9c1xe2x80x9d, cannot effectively use the given frequency in the communication environment considering the multimedia information. For instance, in case that a data terminal receives data or video broadcasting signal utilizing Internet, the data is one-sidedly provided from the corresponding base station, and thus the down-link slots are used, but the up-link slots are not used on the given channel. This causes the use efficiency of the frequency resources to greatly deteriorate.
In order to solve the above problems, there has been proposed a data communication method using a time division duplex (TDD) system for differently allocating the down-link slots and the up-link slots when transmitting required information.
However, various technical problems have been produced in applying the data communication system using the TDD system to the cellular wireless radio communication system. For instance, if the number and the arrangement of the down-link and up-link slots are variably allocated due to an unbalanced amount of traffic, the corresponding base station may fail in random access, or the terminal may be not synchronized with the corresponding base station.
Also, if a terminal in use moves crossing the boundary between adjacent cells in case that the data communication method using the TDD system is applied to a code division multiple access (CDMA) wireless radio communication system, the slots in a slot section where the data communication method using the TDD system is applied may be used as the down-link and up-link slots different from one another for each cell, and thus the interference between the cells may be greatly increased.
Accordingly, the present invention is directed to a data communication method between a base station and a wireless terminal in a wireless radio communication system that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.
An object of the present invention is to provide a data communication method between a base station and a wireless terminal in a wireless radio communication system which does not cause problems in random access by allocating in a frame at least one macro-slot section wherein a static TDD section, in which down-link slots and up-link slots are alternately and repeatedly arranged, and a dynamic TDD section, in which the number and the arrangement of the down-link slots and the up-link slots can be varied, are simultaneously allocated, and which can increase the efficiency of the frequency resources by acquiring the synchronization between the terminal and the corresponding base station.
It is another object of the present invention is to provide a data communication method between a base station and a wireless terminal in a wireless radio communication system which can greatly reduces the interference between cells generated during performing a handoff as the terminal in use moves crossing the boundary of the adjacent cells in case that the time slots in the above-described wireless radio communication system are applied to a CDMA type wireless radio communication system.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims thereof as well as the appended drawings.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, the bidirectional data transmission method between a base station and a wireless terminal in a wireless radio communication system for allocating down-link channels and up-link channels to different time slots having the same frequency band, respectively, the bidirectional data transmission method comprises the steps of varying a channel allocation pattern of the down-link channels and the up-link channels in accordance with a characteristic of a traffic transmitted through the down-link and up-link channels.
In another aspect of the present invention, there is provided a time slot allocating method between a base station and a wireless terminal in a wireless radio communication system for allocating down-link channels and up-link channels to different time slots having the same frequency band, respectively, the time slot allocating method comprising the steps of providing a macro-slot section composed of a plurality of time slots wherein the down-link channels and the up-link channels are allocated in accordance with a specified pattern, and repeatedly applying the allocated pattern for a predetermined number of macro slots.
In still another aspect of the present invention, there is provided a cellular telephone system for allocating down-link channels and up-link channels to different time slots of a same transmission frame between a base station and a wireless terminal, wherein positions of the respective time slots allocated to the down-link channels and the up-link channels between the base station and the radio terminal are fixed in a partial area of a cell.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.